Got the bad news today, headgaskets...

[lvin4jc]

Oh boy. Well I guess i'l be committed to this project now. I had heard about the 4.0 and it's reputation for overheating so when I bought the truck last week I closely inspected the oil and antifreeze for any signs of mixing. I didn't see any of that in either, nothing visually, not by feel, not by smell.

But I got it to my garage today and actually gave it a headgasket test (I was suspicious about my fluctuating temperature gauge) and she failed almost immediately.

So it's scheduled for next week at my friend's shop. A cool $800-$1,000 if the heads aren't toasted.

Well now that this is my reality, what can I do once it's fixed to make sure it doesn't happen again? Was it a factory problem that will be resolved once the repair is completed or should I look at a better cooling radiator or something?



Thanks!

 

[RangerX]

What did you buy?
I've never heard that the 4.0 has a rep for overheating, I've heard it about the 2.9 in older Rangers.
Why not just drive it without repairing?

 

[lvin4jc]

What did you buy?
I've never heard that the 4.0 has a rep for overheating, I've heard it about the 2.9 in older Rangers.
Why not just drive it without repairing?

It's a 1994 Explorer limited auto trans.

Well because when the antifreeze mixes with the oil the oil will lose lubricity and lock the engine up. That'd be my main concern. But it is running quite warm and it's like 50 degrees outside. I don't imagine it'll be driveable in the summer. I bought it for off-roading and I think if you muddy up the radiator a little it would toast her quickly.

- - -

In researching the explorer the head gasket issue was mentioned a lot. As soon as I called my mechanic he said they're prone to that which is what I read all over the internet.

Is that not a common thing?

Thanks!

 

[trashtruck]

by "head gasket test" do you mean compression test? other than removing the head a compression test is the only way to verify the integrity of the gasket, unless i missed something some where.

 

[Rhett]

should I look at a better cooling radiator or something?!

4.0 OHV OEM radiators, especially the "super cool"/tow pkg radiators, cool that engine quite well with the clutch fan and shroud. Our radiators have a good reputation. Guys do 5.0 conversions and have kept the 4.0 radiator and it cooled just fine, that's how effective it is. Anything can overheat, no matter how good, if coolant gets low and/or passages clogged, or t-stat stuck closed.

Are you sure you don't just have a bunch of air in the system? That can cause the fluctuations you describe. Of course, if your head gasket is bad, you could have both -- enough coolant leaked into the oil to where you have air in the cooling sys as well as in the crankcase. Any details on the kind of test did they ran?

 

[RangerX]

Oh boy. Well I guess i'l be committed to this project now. I had heard about the 4.0 and it's reputation for overheating so when I bought the truck last week I closely inspected the oil and antifreeze for any signs of mixing. I didn't see any of that in either, nothing visually, not by feel, not by smell.

But I got it to my garage today and actually gave it a headgasket test (I was suspicious about my fluctuating temperature gauge) and she failed almost immediately.

Maybe I'm not understanding something, but you say there's no sign of oil in the radiator, and no sign of antifreeze in the oil, so why do you think that mixing is happening??
We def need more detail on what test you ran...

 

[lvin4jc]

Sorry for the confusion all. I ran a test with the blue test fluid through the radiator cap with the fancy turkey baster thing. We've used it for years to determine if a headgasket is bad. If you've never seen one they have a blue chemical that turns yellow in the presence of exhaust gasses. Depending on how bad the headgasket is you might see it turn yellow quickly or see it turn really, really yellow. Mine turned yellow in less than 10 seconds. I literally tried the tester at the end of an exhaust pipe of a running vehicle today and it took longer to turn yellow there.

Tester looks like this - http://www.uniquetruck.com/p-33816-...iateID=10056&gclid=COzQmMm9jNMCFZE1aQodb7wPKg

So this means I have exhaust gas in the coolant system. Should be head gasket, cracked block or cracked head.

In talking to my mechanic friend today we finally decided that maybe it would be worth it to drive it for a little bit and see what happens. I mean, the oil does look good and the antifreeze does too, haven't driven it enough to know how much antifreeze is leaking. If I could get it to stay cool then maybe it could go for a while?

This thing was parked for a while and one thing he mentioned that I have yet to check is to see if the fan clutch is working, maybe it's not even turning the fan?

I think i'm going to change the oil, flush the cooling system and verify the fan. If it stays warm I might even throw a new radiator in it. All this might make it run cool and the antifreeze may actually stay out of the oil (still my main concern) but I don't know how you get around the fact that there's exhaust gas in the radiator.

P.S. He also suggested that I pressurize the cylinders with an air compressor and see if the antifreeze in the radiator bubbles just to make sure. I might try that too.

 

[RangerX]

It all comes down to how much money you have. If you have it, and you want a tight fresh engine, then do the fix. If you can't see throwing a grand or more on a 23 year old truck that's going to be dirt toy, then just drive it.
My thought is, if you couldn't see it or smell it or feel it, how bad is it really? Not urgent, IMO. And it's not the cause of the fluctuating temp. Check everything else cooling system related that you mentioned, that's all easier, cheaper, and more likely the issue.
Just my two cents.

 

[lvin4jc]

If you can't see throwing a grand or more on a 23 year old truck that's going to be dirt toy, then just drive it.

My thought is, if you couldn't see it or smell it or feel it, how bad is it really? Not urgent, IMO. And it's not the cause of the fluctuating temp.

Yeah, this.

I guess i'll drive it a bit more and see how bad it really is. I guess I haven't considered a slightly blown head gasket before. In my mind they're good or bad. But this truck is running well so that does make me wonder if it's livable, or livable for a while anyway.

What we were discussing today is that as long as the oil continues to look good then the only thing that's being risked is that the head gasket would blow out completely. In that case it would need replaced but that's what i'm already looking at now so... why not try it a little while and see if it gets worse or is OK?

I'll pull her out on the road tomorrow, look at it a little closer at the shop and report back!

 

[Rhett]

When you change the oil, you could also collect mid-stream, and send it to Blackstone Labs. They could tell you if there is any coolant in the oil. It's pretty cheap too.

 

[larrydd999]

I've just replaced the fan clutch for the 3rd time in my '92 XLT due to an overheating issue that was causing coolant loss (the pressure test showed no problem). The first clutch went bad a couple of months ago and the aftermarket 'generic' one was better but not much. I purchased a 'name brand' one (not OEM) and now it's fine. Just a FYI. If you do decide to replace the fan clutch, it's a fairly simple and quick job - as long as you can get the nut loose (yes I bought the tool set).

 

[lvin4jc]

Well, I drove it on today and did a few things on it.

The first thing I did was to re-test the radiator with my tester kit. I tried and tried to get it to fail. It finally turned kind of a blue-green color. It starts blue and is supposed to turn yellow if it detects exhaust gasses. Not sure how conclusive that was?!?

I poked around the engine compartment with an infared thermometer. The hottest reading I could get was on the upper radiator hose. It only ranged from 145-155 Fahrenheit while the gauge slowly but surely bounced between "O" and "L" of NORMAL.

I changed the oil and filter with new.

I flushed and filled the cooling system, verified that the fan is in fact turning on, it is.

After that I retested for head gasket with the chemical tester just like the two times before. After all this it won't budge from the blue it starts as. It's passing this head gasket test with flying colors. Not sure how or why this is happening, very strange.

I also inspected the radiator. With a hose pointing from the back to the front there's not a lot of water coming through the fins. With a light behind the radiator I can see the light from the front but it's in generally just decent condition. Probably not the best or most efficient but I would think that would lead to overheating, not the up and down the gauge is reading.

I can't remember if i've mentioned this before but if it's getting warm and you rev the engine the temperature gauge drops quickly and reliably. Now i'm wondering if that's actually making it run cooler or changing the resistance on a shorted wire or something making it look like it's cooling things down. I did pull a heater hose and crank the engine to make sure the water pump was forcing water around in there. It did shoot water out of it so I have to think the water pump is working.

- - -

So now i'm wondering if the gasket is OK. Also thinking that my gauge might be on the fritz for coolant temp. Thinking about adding another temp gauge to see what it says and if it's consistent.

 

[timtimtimajim]

Also thinking that my gauge might be on the fritz for coolant temp. Thinking about adding another temp gauge to see what it says and if it's consistent.

This right here.

I used to think I had an issue with the engine running hot. The gauge would go up and just stop right in the middle of NORMAL. I replaced the sending unit for my factory gauge which seemed to make the gauge read slightly more accurate, but I still wasn't sure how accurate as there are no numbers on the factory gauge. So I put an aftermarket gauge in (used a heater hose adapter for the sending unit) and come to find out the engine is running right at the thermostat temperature (190) and only climbs to 195-200 if it's a hot day in traffic.

So if I were you, I would definitely think about adding an aftermarket gauge before going any further. It'll be more accurate and will help tell you if you really have an issue or not.

 

[natenkiki2004]

Those chemical tests are unreliable. ScannerDanner has a demonstration on it where there's an obvious head gasket issue (rapid boiling in the radiator, misfire and I believe white smoke out the exhaust) that was verified with a gas analyzer. Couldn't get the blue fluid to turn yellow even repeating the test several times.

A compression test is a good idea but so is a leakdown test. If all the cylinders pass a leakdown test then your problem is definitely elsewhere. A leakdown test will tell you where combustion/compression is escaping to. Bubbles in the radiator when doing a leakdown means a failed head gasket for sure.

For what it's worth, I had blocked one side of my heater core and that caused weird issues with the temp gauge. It would get really hot then cool down, back and forth like that for 20 minutes on a trip, no matter speed or engine load.

Do a leakdown test first. In fact, the shop you got an estimate from should do it to diagnose the issue rather than throw a cost at you. That kinda tells me that they're just quoting a job and not really concerned about figuring what's wrong to begin with.

 

[Rhett]

I flushed and filled the cooling system, verified that the fan is in fact turning on, it is.

Did you purge the system of air? It almost sounds like either air in the sys or the stat not operating well. Even so....I have seen my OEM temp gauge wander from time to time...they aren't very reliable. Aftermarket temp gauge is always a good idea.

 

[lvin4jc]

Aftermarket temp gauge will be here tomorrow.

Also have a friend that just bought a leakdown tester so i'll try that too.

In the meantime, running well, still no misfire even with a cold start on a 38 degree morning. Sounds good and smooth. Factory temp gauge still wandering from O-L but never passing the L. No driveability issues, especially that would indicate overheating.

Thanks guys, very helpful forum here, glad I found it!

 

[Centaurious]

Jack up the front until the radiator cap is higher than the base of the windshield. Then run the engine and hold at around 2000 rpm 5 or 6 times for 10-15 seconds. This should move the air pockets into the radiator.

The shops offer a replacement Temp Sending Unit Wire Harness, a wire with the correct right angle stud connector. I need to replace mine because of corrosion that causes intermittent readings but it is very tight spacewise to replace.

 

[kmack]

Here's a story not directly related to an Explorer, but directly related to Ford Temp Gauges...

We used to have an '85 motorhome with a 7.5L V8 (460 cid) that always "ran hot". Gauge was always between the "A" & "L" of "NORMAL."
Over the course of a year, we replaced (with new) all radiator hoses, radiator, thermostat, thermostat housing, fan w/ clutch, overflow tank, heater core hoses. The only thing not replaced on the cooling system was the heater core, because I didn't want to pull the dash! Temp gauge never got off the "A" or "L".

I ended up putting a manual temp gauge in one day and it showed 190*F all day long, all summer long, highway driving or sitting in traffic. Go figure!